You can find the Resolutionandmode configuration under the
Graphics tab. There you can switch between full screen mode and
windowed mode. In the case of full screen, you can choose the resolution
from a list of supported resolutions in a drop down menu. If you choose
windowed mode, you can enter the resolution you want. You can also
choose whether the window should be resizable or not. In order to switch
from full screen mode to windowed mode during the execution, use the key
F11.

This setting governs the size of the textures, the complexity of the
models and also the quality of the graphical effects (lightglow,
lensflare, etc.). Here are the differences:

High Contains some high-resolution textures (4K) and specular and normal maps for most celestial bodies. Planets and moons have a high vertex count. Graphical effects use a large number of samples to get the best visuals.

Normal contains lower resolution textures (2K when available) and some specular and normal maps are deactivated. The graphical effects use a reasonable amount of quality for nice visuals without compromising the performance too much.

Low Offers a noticeable performance gain on less powerful systems. Same textures and model quality as in the Normal setting. The volumetriclight effect is turned off completely and the lensflare effect uses a low number of ghosts.

In the Graphics tab you can also find the antialiasing
configuration. Applying antialiasing removes the jagged edges of the
scene and makes it look better. However, it does not come free of cost,
and usually has a penalty on the frames per second (FPS). There are four
main options, described below.

If you choose this no antialiasing will be applied, and therefore you
will probably see jagged edges around models. This has no penalty on
either the CPU or the GPU. If want you enable antialiasing with
overrideapplicationsettings in your graphics card driver
configuration program, you can leave the application antialiasing
setting to off.

FXAA - Fast Approximate Antialiasing

This is a post-processing antialiasing which is very fast and produces
reasonably good results. It has some impact on the FPS depending on how
fast your graphics card is. As it is a post-processing effect, this will
work also when you take screenshots or output the frames. Here is more info on FXAA.

NFAA - Normal Field Antialiasing

This is yet another post-processing antialiasing technique. It is based
on generating a normal map to detect the edges for later smoothing. It
may look better on some devices and the penalty in FPS is small. It will
also work for the screenshots and frame outputs.

MSAA - Multi-Sample Antialiasing

As of version 1.0.1 MSAA is not offered anymore. This is implemented
by the graphics card and may not always be available. You can choose the
number of samples (from 2 to 16, from worse to better) and it has a
bigger cost on FPS than the post-processing options. It also looks
better. However, this being reliant on a special multisample frame
buffer in the graphics card makes it not available for screenshots and
frame outputs.

This option limits the frames per second to match your monitor’s refresh
rate and prevent screen tearing. It is recommended to leave it enabled
unless you want to test how many FPS you can get or you want to fry your
card.